Non-syndromic cleft secondary palate (CP) is one of the most common human birth defects. It has a very complete etiology that includes strong genetic, likely polygenic, and environmental contributions. Although many embryological studies in model organisms and linkage and association studies in humans have provided insight into this complexity the developmental and genetic basis for normal palate development remains incompletely understood. The study of palatal development in isogenic mouse strains carrying Mendelian mutations in a controlled environment avoids confounding influences as allelic heterogeneity and environmental insults. Specifically, I propose to initiate studies of mouse mutation with an isolated cleft secondary palate phenotype, cleft palate only 1 (cpo1), as an entry point into the understanding of a specific gene whose function and interactions in a genetic pathway(s) is essential to norm; palatogenesis. I have used a positional cloning strategy to rapidly clone the causative gene for cpo1, the Prdm16 (alias, Mel1) Zn-finger transcription factor. I will use the cpo1 mutant to elucidate the specific developmental defect in palatogenesis caused by the Prdm16 gene mutation and analyze the pattern of Prdm16 gene and protein expression during embryogenesis and palatogenesis in wildtype mouse embryos. Using in situ hybridization and immunohistochemistry, I will assay the expression of genes and proteins that mark specific stages and structures during palatogenesis to identify putative members of a common genetic pathway affecting normal palate development. Finally, downstream targets and DNA-binding sites of the Prdm16 protein will be identified through hybridization to DNA binding arrays and co-immunoprecipitation experiments.